Acoustic barriers based on latticces of absorptive cylinders

This works reviews the advances in the design and practical realization of acoustic barriers made of two-dimensional lattices of cylindrical scatterers. These building units are here studied with absorptive properties. Therefore, the attenuation from the barrier is obtained from two combined mechanisms: scattering Bragg from the lattice and absorption by the cylinders. Several building units have been essayed in order to study the insertion loss of the fabricated barriers. Starting from rigid cylinders, cylinders made of rubber crumb and cylindrical shells with micro-perforations have been fabricated and characterized. It is demonstrated that lattices made of micro-perforated shells provided the best performance. An algorithm of optimization is developed and applied in the design of structures adapted to attenuate noise traffic very efficiently.